Biochemical oxygen demand continual detecting apparatus



March 19, 1968 HIDEO SUZUKI BIOCHEMICAL OXYGEN DEMAND CONTINUALDETECTING APPARATUS Filed Dec. 16, 1964 INVENTOR United States atentOilice 3,374,065 Patented Mar. 19, 1968 ABSTRACT OF THE DISCLOSURE Anapparatus for the automatic detection of the B.O.D. value, comprising acontainer and means for injecting a the volatile organic acid alkalinitycontained in the stream to be measured.

After due experimental studies performed by the inventor, it wassuccessfully discovered that organic substances in water streams relateto the B.O.D. value and usually consist of acetic acid, propionic acid,butyric acid, etc; and that -50% of the B.O.D. value may always becorrelated with the lower fatty acid content.

Also, fatty acids having comparatively large molecules together withunsaponifiable matters other than suspended matters may, however,contain, fatty acids which are always the central base of thosesubstances.

In order to clarify the aforesaid description, the following comparativetable between the rate of volatile acidic alkali and the measured valueof the B.O.D. is provided:

Chemical Aiter Bio- Kind of soils (p.p.m.) River- River- Rivertreatedchemical Drain Drain water water water urinate treatment (A) (B) waterVolatile acid alkalinity by direct titration 26.9 19.8 15.8 607.6 75.234.5 44.2 Organic acid by steam distillation method 43.7 23.4 13.2 380.6127.2 65.0 54.9 34. 3 30. 9 9. 1 1,330.0 61. 3 117. 5 108. 1

test material into the container. Means are provided for injecting anon-organic acid into the container to form a mixture. Means for mixingand heating the mixture causes a removal of the basic group, such ascarbonate, bi-carbonate or carbonate anhydride, etc. During this stage,means for continuously detecting the lowering pH value causes a valve toclose, thereby closing the nonorganic acid injecting means when a low pHvalue is reached. Means for injecting an alkaline having a predetermined density into the mixture is provided and a recording meter isprovided for showing the pH value increase. A measuring means determinesthe B.O.D. value by measuring an operating period of the alkalineinjecting means over a pH value range indicating the volatile organicacid alkalinity.

The present invention relates to an apparatus for continuously detectingand estimating B.O.D. (Biochemical Oxygen Demand) value existing indrainages, rivers, etc.

In spite of a serious need for sufficient detection of the B.O.D. valuein the public health field, there has never been, heretofore, anappropriate method for estimating the B.O.D. value on a continual basisdue to a difficulty of measuring the varying B.O.D. in flowing drainwater.

It has been desired to maintain drainages and rivers within :apredetermined or normal B.O.D. value; however, an exact measurement ofthe B.O.D. value in water streams could not be satisfactorily achieveddue to the continuous change of the B.O.D. value.

It is an object of the present invention to provide an epoch makingapparatus for continuously estimating the B.O.D. value in water streams.

It is another object of the present invention to provide an apparatuswhich substantially utilizes a close chemical relation which existsbetween volatile organic acid alkalinity and the B.O.D. value.

In accordance with the present invention, the B.O.D. value in waterstreams can be precisely measured continuously, even though the B.O.D.value is irregular.

A further feature of the present invention is that the B.O.D. value canbe indirectly measured by obtaining As apparent from the above table, amutual relation is confirmed between the volatile acidic alkali and theB.O.D. value.

In order to estimate the B.O.D. value in water streams, the presentinvention provides a detecting apparatus which essentially consists of acomplete line of an automatic pumping device together with other meanswhereby the volatile organic lacid alkalinity and the B.O.D. value canbe automatically measured with a continuous recording system.

In detail, this apparatus is constructed with a testing tube, anautomatic sampler which takes the proposed sample in the base of aperiodic time interval, a pH meter, an acid reservoir, .an alkali tank,a pump for a predetermined volume, a recorder for the B.O.D., etc.

With these and other objects in view, which will become apparent in thefollowing detailed. description, the present invention will be clearlyunderstood in connec tion with the accompanying drawing, in which:

FIGURE 1 is a schematic diagram of an embodimnt of the presentinvention; and

FIG. 2 is a graph showing a mutual relation between the B.O.D. value(p.p.m.) and the volatile organic acid alkalinity. I r 1 Referring nowto the drawing, a test material is initially conducted by a pump 15 intoa testing tube 5 and an electric switch 1 is turned on.

A sampler-timer 2 is then actuated and an acid is supplied into thetesting water of the testing tube 5. At the same time, valve 6, attachedto an outlet pipe of the test material 5', and provided on the testingtube 5, is closed and a mixing treatment with heat is performed by mixer7 together with heater 8 as switch 8' is turned on. At the moment whenthe pH contained in the test material shows a lower value than anydesired value, for instance, such as 3.5, an indicating signal istransmitting to a pH meter 10 by means of a glass-electrode 9 on which afixed thermostat is contained in the testing tube 5, whereby a valve 3of an acid tank 4 is closed by an operation of a shifting switch 11which is connected to the pH meter 10.

On the other hand, heater circuit 8 'of the testing tube 5 issimultaneously cut within five minutes, being effected by the timer 2,and an alkaline solution having a 3 normal cardinal number is suppliedinto the testing tube 5 at a constant speed by means of a quantitativepump 13 fixed in the tank 12. If the pH contained in the test materialshows a value, for instance 4, an operation of a B.O.D. indicator 14 iscommenced.

The B.O.D. indicator 14 is designed so as to record an operating periodof the quantitative pump 13, and accordingly a volatile organic acidalkalinity is shown in the indicator through the quantity of thealkaline solution supplied by the quantitative pump 13.

Thus a scale on the indicator may be directly read as the B.O.D. value,for instance, from a reference line A.B. y=2.18x+34.8 (where, y=B.O.D.in p.p.m., and x=volatile organic alkalinity in ppm.) as shown in FIG.2. Further, OY and OX in FIG. 2 respectively show the B.O.D. in ppm. andthe volatile organic acid alkalinity in p.-p.m.

Assuming the pH becomes 7, then the alkaline quantitative pump 13 stopsand the indication of the B.O.D. recording indicator 14 is terminated.Then, the valve 6 of the outlet pipe 5 for the test material on thetesting tube 5 opens and supplies the test material into the testingtube 5. At this moment, a test material, readily measured, is exhaustedthrough the outlet pipe 5' being effected by an operation of the pump 15:being controlled by the sampler-timer 2. Then, 'by supplying the testmaterial into the testing tube 5, another test material suppliedpreviously is accordingly replaced and a normal water level of the testmaterial may be maintained in the testing tube since the pump will beautomatically stopped. If the sampler pump 15 suspends its operation,the same state as the commencing operative state occurs in which theelectric switch is on and the aforesaid process can be repeated.

Now, for a further appreciation and better understanding of the presentinvention, three experimental examples are provided.

Example 1 With a 500.00 cc. testing tube, successive titration of acidand alkali of which the cardinal number is N/lO was performed at achemical treating laboratory on drainage.

After twelve hours of successive operation with ten minute timeintervals for thirty two times, the reference line shows y=1.33x+605.7(where, y=B.O.D. in p.p.m., and x=volatile organic acid alkinity inppm). The scale indication on the recording paper detected the referenceformula.

Example 2 With a 300.00 cc. testing tube, the B.O.D. value existing inthe neighborhood of an overflowing reservoir outlet was measuredtwenty-one times. Each measurement was processed for fifteen minuteshaving been kept continuously for twenty-four hours, successively.

The reference line detected was y=2.18x+34.8 (y=B.0.D. in p.p.m., andx=alkaline degree of organic acid in ppm.)

Example 3 With a 300.00 cc. testing tube, and fifteen minutemeasurements, the B.O.D. value in river water was successively madetwenty-two times in two days. The respective 4 time intervals betweenexperiments were two hours. The reference line showed y=1.55x0.77(y:B.O.D. in p.p.m., x=volatile organic acid alkalinity in p.p.m.).

As is apparent from the above examples, the present continuous B.O.D.detecting apparatus can be easily utilized for detecting the B.O.D.value such as, for example, from river water, drain water and any typeof sewages by means of classifying scales, testing tube capacities,cardinal numbers of acid and alkali of the recording form into severalgroups depending upon the proposed drainage to be tested.

The present B.O.D. detecting apparatus provides a remarkable means fordetecting B.O.D. in river water, drain water and any other type ofsewages by usefully utilizing a close chemical relationship betweenvolatile organic acid alkalinity and the B.O.D. value.

The present invention successfully provides an inventive detecting forthe B.O.D. value without being affected by the continuous changes of thewater quality.

While I have disclosed one embodiment of the present invention, it is tobe understood that this embodiment is given by example only and not in alimiting sense, the scope of the present invention being determined bythe objects and the claim.

What I claim is:

1. An apparatus for the automatic detection of the B.O.D. value of atest material comprising a container used as a testing tube,

means for injecting the test material into said container,

means for injecting a non-organic acid in o said container to form amixture,

means for mixing and heating said mixture,

means responsive to a predetermined low pH value for closing saidnon-organic acid injecting means, means for injecting an alkali having apredetermined density into said mixture at a predetermined rate,recording meter means for showing the pH value increase, and

determining the B.O.D. value by recording the time during which thealkali is injected until the pH reaches a predetermined high value,whereby the total alkali added is determined and is a measure of thefatty acid content of said test material and correlated to the B.O.D.value thereof, whereby the B.O.D. value of said test material isdetermined.

References Cited UNITED STATES PATENTS 2,928,782 3/1960 Leisey 23253 X3,073,682 1/1963 Lindsley 23253 3,192,017 6/1965 Kruger 23253 3,246,9524/1966 Dawe 23253 OTHER REFERENCES Gaffney et al.: Biochemical Oxidationof the Lower Fatty Acids, Water Pollution Control Federation Journal,vol. 33, pp. 1178-1181, November 1961.

MORRIS O. WOLK, Primary Examiner.

R. E. SERWIN, Assistant Examiner.

